Louis C.K.

I love Louis C.K. He's definitely one of my favorites, but my all time favorite is George Carlin. The man was a fucking genius, and in addition to making me laugh, listening to him at a young age taught me a lot about life.
I've been very big into stand-up for years now, and my list of favorite comedians is almost never-ending. Off the top of my head, I like: Nick Swardson, Greg Giraldo, Brian Posehn, David Cross, Mitch Hedberg, Doug Benson, Patton Oswalt, Todd Barry, Kyle Cease, Robert Schimmel, Jim Gaffigan, Brian Regan, Paul F. Tompkins, Lisa Lampanelli, Aziz Ansari, Bill Burr, Steve Byrne, Adam Carolla, Andrew Daly, Christian Finnegan, Rich Vos, Nick DiPaolo, Kevin Hart, Jay Mohr, Eugene Mirman, Daniel Tosh, Todd Glass, and ton of others.

Bill Hicks 
Patton Oswalt 
David Cross 
Maria Bamford 
Zach Galafinakus 
Mitch Hedberg 
Steven Wright 
Eddie Izzard 
Lewis Black 
Ralphie May 
Sam Kinison 
Sam Tripoli 

Louis C.K 
George Carlin 
Dave Chappelle

I haven't cared much for stand-up for years now, but I am a fan of Jim Gaffigan.
 
Of course my favorite is Rodney Dangerfield.

Louis C.K. is pretty funny, so is Jim Gaffigan. 

Mitch Hedberg is probably my favorite. Such a shame that he died :<
 
I really like Louis CK, though. I'm not entirely sure I can think of another comedian that I'd actually enjoy. Doesn't happen often that I watch that stuff.

David Cross and Louis C.K. are a few of my favorites.

Louis C.K and Russel Peters. Kevin Hart is also funny as hell, but I have only seen one of his stand-ups.

Honestly, I don't know of any currently performing stand-up comics that I can enjoy with consistency (there are a ton that are great here and there) other than Louis C.K., Jim Gaffigan, and (most of the time; he's really good at going for the most shocking material) Stephen Lynch. 
 
Also, any one that doesn't watch Louie (Louis C.K.'s show on fox, the second season's been picked up) really should go back and watch it; it's outstanding.

Louie CK for sure. 
 
Bill Hicks is one of the best ever, and without question a huge influence for a lot of modern comics. 
David Cross 
Patton Oswalt 
Eddie Izzard 
George Carlin 
Paul F. Tompkins 
Ricky Gervais 
Brian Posehn 
Almost any comic that's been on Comedy Death Ray Radio

I hate standup, but CK is by far the most tolerable. Other than stand up, the dudes hilarious. His shows are amazing.

Dylan Moran's pretty good.

Russel Peters is my personal favourite although I also like Dane Cook (I don't care if he's a douche, he's funny).  
 
EDIT: I also really like Murray from Flight of the Conchords (Rhys Darby)

Glad to see Eddie Izzard get some props here.
 
Eddie has always been my favorite. I love his stream-of-consciousness delivery. I've seen all of his specials, and he's the only comedian I've ever made a point of seeing live. Really no one else like him around.

Daniel Tosh
Louis C.K.
 
Don't watch that many comedians.